OT, but you had to give 1.5 Vcore to get up to 4.2? Wow! Talk about diminishing returns, right? I managed 4.0 on my 1055T with 1.41 Vcore. That was up from a stock clock of 2.8 and stock Vcore of ??1.38!!

Yup, if I remember correctly I was running 4.0ghz at 1.4 too. Anything over that and you gotta really pour the coal to them. So it's really a matter of finding your maximum (and what you feel is comfortable) vcore/temp combo and see how high you can push the frequencies. I used to push the frequency first and bump vcore after. Now that it's under water I go the other way around.